Endosulfan has been used extensively for pesticide control in tangerine orchard. It causes human health effect and environmental impact from aboundant usage and potential for environmental transport. The objective of this study is to reduce the movement of endosulfan in tangerine orchard soil by sorption process. Soil amendment by sludge has been reported to affect pesticide binding, transport and ultimate distribution in soil profile. In this experiment, soil from Mae-ai District, Chiang Mai was used to represent tangerine rchard soil. Three types of wastewater treatment sludge were studied in batch partitioning experiment to identify their sorption abilities. They are pig farm, municipal wastweater treatment sludge and food industrial-sweet corn canning sludge. In the study, the organic content of soil and sludges are 1.85% and 42.51-53.33%, respetively. The results showed that the sorption coefficient (Kd) of soil was 47.5 mL g-1, while the Kd of sludge from pig farm, municipal wastewater treatment plant, and sweet corn canning factory were 1,755.5, 466.9, and 707.7 mL g-1 respectively. WWTS from pig frm has highest sorption coefficient value and low desorption rate, thus it was chosen to be the cover material in soil column experiment. Soil columns were prepared by packing tangerine orchard soil in glass columns and applied. The results showed that endosulfan was mainly sorbed in the WWTS layer, while it moved down the soil profile in columns without WWTS. The results suggested that the contamination of endosulfan could be minimized by cover the soil surface with wastewater treatment sludge.
